Process for treating petroleum oils



L. C. HUFF PROCESS FOR TREATING PETROLEUM OILS Feb. 17, w 1931. 1

Original Filed May 17, 1922 ku ha u QMQWSQ I 13mm]! Cliff Patented Feb. 17, 1931 4 UNITED STATES PATENT OFFICE LYMAN C. HUFF, OF CHICAGO, ILLINOIS, ASSIGNOR TO UNIVERSAL OIL PRODUCTS COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF SOUTH DAKOTA PROCESS FOR TBEATING PETROLEUM OILS .OIiginal application filed May 17, 1922, Serial No. 561,585. Divided and application filed May 7, 1925, Serial No. 28,539. Again divided and this application filed February 25, 1929. Serial No. 342,472.

This invention relates to improvements in a process and apparatus for treating petroleum oils, and refers more particularly to a process for the conversion of relatively heavy oils into lighter oils such as gasoline and the like.

This application is a division of my coglending application, Serial Number 28,539,

ed May 7, 1925, which latter application 1s in turn a division of an application filed by me on May 17 1922, Serial Number 561,585.

Among the objects of the invention are to provide a process in which the oil is heated to a conversion temperature in a heating. zone and is passed to a vaporizing stage in which the lighter portions are separated out and pass off in vaporous form, the heavier liquid being drawn off as residual material.

A further object of the invention is to provide an improved method of heating the oil and in the arrangement of the apparatus used therefor.

The single figure is a diagrammatic side elevational view of the apparatus with parts and section.

Referring to the drawing, the oil to be treated is introduced from any convenient extraneous source through the line 1 controlled by the valve 2 and is passed through the upper layer of tubes 3 positioned near the top of the a tube compartment i ofthe furnace 5. The furnace 5 comprises a combustion chamber 6 in which the burners 7 are situated and the tube compartment 4 in which the heating coils are positioned. The gases of combustion pass from the chamber 6 through the ducts 8 downwardly through the compartment 4; passing off to stack through the flue 9.

The oil after being subjected to the hottest combustion gases entering the tube compartment from the combustion chamber, passes down through the line 10 through which it is introduced to one of the lower tubes 11 of the bank of tubes which are positioned in the tube compartment. The oil introduced to the lower tube flows successively through the continuous coil working its way upwardly from the cooler portion of the tube compartment toward the hottest portion which is the top.

I By the time it has reached the upper tubes, its

temperature has been raised sufficiently to cause a conversion of the oil, at which time it is passed through the transfer line 12 which is connected to the vaporizing chamber 13. The transfer line terminates in a pipe 14 which extends well into the center of the vaporizing chamber in the form of a spout, the end of.which is turned downwardly to introduce the vaporous fluid oil into the central part of the vaporizing chamber, thus preventing any collection of carbon about the transfer line at the point at which it enters the chamber.

The vaporizing chamber preferably comprises a vertical cylindrical chamber mounted within insulated walls 15. At the top is a clean-out manhole 16 and a similar manhole 17 situated at the side. The lower portion of'the chamber is preferably conical, a residuum line 18 controlled by valve 19 being situated at the apex of the cone for drawing off the heavier unvaporized oil. An emergency residual drawoff line 20 controlled by 'valve 21 is inserted into the side of the chamber to draw ofl the residual substance should the lower line become clogged or obstructed.

The insulation about the vaporizing chamber consists of materials such as an inside layer of fire felt, an intermediate layer of sponge felt with an outer casing of steel plate. An insulating wall of this character not only serves to more efi'ectively retain the heat of the chamber but absorbs much less of the heat from the process than does a brick or masonry insulating wall.

Near the lower part of the evaporating chamber in the sides of the insulating walls are situated air dampers 22 and similar dampers 23 near the top of the chamber. By manipulating these dampers the cooling air permitted to circulate about the chamber may be controlled and'the temperature of the vaporizing chamber likewise regulated.

The vapors evolved in the chamber pass off through a line 24 controlled by a valve 25 to the dephlegmator 26 where they are subjected to a refluxing action. After (lephlcg mation, the still vaporous products pass off from the top of the dephlagmator through the line 27 controlled by the valve 28 to the water condenser coil 29 mounted in condens- The reflux condensate separated out in the dephlegmating chamber is returned through the line 38 controlled by valve. 39, and is charged with the incoming raw oil to the line 10 where it is subjected with the oil to heat treatment in the heating zone.

When cracking. hydrocarbon oil, particularly the more refractory oils, it is often necessary to subject them to temperatures having a very deteriorating effect upon the furnace tubes. This is particularly true where the combustion gases come in direct contact with the heating tubes and with those tubes which contain the hottest oil. By excess heating, the tubes are not only weakened but are pitted and must be continuously replaced if some provision is notmade for tempering the heat of the combustion gases that come in contact with the tubes containin the hottest oil.

is a remedy for these difliculties as shown in the drawing, the incoming oil is circulated in an upper layer of tubes which come in contact with the hottest combustion gases coming through the ducts 8 which connect with the combustion chamber 6 with the tube chamber 4. Thus the cool oil is subjected to the hottest furnace temperature, and by circulating the cool oil through this layer of tubes 3 the oil charge is considerably heated prior to its introduction to the main bank of tubes positioned just below the upper preheating tubes. Subsequent to the preheating of the oil, it is passed down through line 10 which is heavily insulated, to the lower tubes in the furnace and its travel is then upwardly through the continuous coil until it flows through the tubes just below the upper preheating tubes. At this point the oil is at its highest temperature, but the tubes containing the hottest oil are shielded from the hottest furnace temperature by the overlaying preheating tubes which tend to temper somewhat the excessive heat of the combustion gases. The hot oil after being raised to a conversion temperature passes from the tubes through the transfer line 12 into the vaporizing chamber 13, where a greater part of the conversion takes place. The vapors evolved pass off through the vapor line 24 and after being refluxed and condensed are collected as distillate in the receiver 33. The

reflux condensate is returned and recycled with the incoming oil charge.

The temperature of the vaporizing cham her is carefully regulated by the dampers 22 and 23 which control. the circulation of air within the circular wall 15. Instead of maintaining the oil at a level in the vaporizing chamber, ,it is intended that the residuum and heavier unvaporized products be continuously drawn ofi so as to prevent the collection and accumulation of carbonaceous matter in the bottom of the chamber. Where the oil is maintained at a level in the chamher the carbon collects on the side walls beneath the oil level while above the oil level in the vapor space there is very little collection of carbonaceous material. Thus by continuously drawing off the liquid oil and precipitated carbon which is contained therein in a suspended state, theperiod of operation is considerably lengthenedas the process a will not have to be slowed down for cleaning.

ranging from 700 to 900 F., and pressures of from 50 to 200 pounds, a substantial yield of from 30 to 50% high grade distillate having a Baum gravity of from 48 to 52 may be obtained.

It has been found that the vapors in the re action chamber of a cracking system have a tendency to stratify, the lighter ones going to the top, and the heavier onescollecting' near the bottom of the chamber. By locating the discharge from the heating tubes in the bottom of the vaporizing stage, the fluid oil which is introduced thereto separates, the

vapors therefrom rising through the stratified zone of gaseous vapors, and the residual liquid substance being drawn off from the bottom of the chamber. The passage of the vapors through the stratified area has a tendency to separate the lighter and heavier vapors conforming with the zones of the Stratified area.

By regulating the circulation of air about the chamber, the condensation of the vapors in the chamber is controlled. The condensate produced therein flowing/down the sides of the chamber will carry with it any precipitated carbon which has a tendency to collect or adhere to the side of the chamber. The liquid residue'and carbon containing condensate is drawn off to prevent any accumulation of liquid in the bottom of the chamber.

What I claim as my invention is 1. In processes for cracking hydrocarbon oils to produce from higher boiling point oils lower boiling point products of the character in which the oil is raised to a cracking temperature while advancing through a heating coil, thence introduced into an enlarged reaction zone from which vapors and liquid oil are separately removed and return. of the latter to said coil prevented, the vapors subjected to reflux condensation, the reflux condensate returned for re-treatment in the process, the improvement which comprises introducing the heated hydrocarbons from the heating coil into the lower portion of the reaction zone and so controlling the rate of withdrawal of unvaporized liquid from the reaction zone as to prevent any accumulation of liquid in the bottom of the reaction zone, and maintaining substantial superatmospheric pressure on the oil in said heating coil and reaction zone.

2. In processes for cracking hydrocarbon oils to produce from higher boiling point oils lower boiling point products of the character in which the oil is raised to a cracking temperature while advancing through a heating coil, thence introduced into an enlarged reaction zone from which vapors and liquid oil are separatel removed and return of the latter to said c011 prevented, the vapors subjected to reflux condensation, the reflux condensate returned for re-treatment in the process, the improvement comprising withdrawing the unvaporized liquid oil from the reaction zone continuously and at a rate adequate to prevent any accumulation in the bottom of the reaction zone, and maintaining substantial superatmospheric pressure on the oil in said heating coil and reaction 3. A process for cracking hydrocarbon oil a heating zone, thence introduced to a reaction chamber from which vapors and unvaporized oil are separately removed and return of the latter to said zone prevented, the vapors subjected to partial condensation to separate heavier constituents therefrom to be subjected to further cracking, the improvement which comprises preventing any accumulation of unvaporized liquid oil in the reaction zone by continuously and rapidly Withdrawing the non-vaporous liquid from the reaction zone, and maintaining substantial superatmospheric pressure on the oil in said heating zone and reaction chamber.

5. The process of cracking petroleum oils which comprises continuously passing such oil in a restricted stream through a zone wherein the oil is heated to a cracking temperature,

thence delivering this restricted stream of oil constituents into a. reaction zone, continuously removing vapors, and liquid oil from said reaction zone Without permitting any substantial portion of the liquid oil so removed to mingle with the oil of said restricted stream, effecting the removal of the liquid oil at a rate adequate to prevent during normal operation of the process the accumulation of any appreciable body of oil in such reaction zone, subjecting the vapors evolved from the oil to reflux condensation, returning reflux condensate thus derived to said restricted stream, and maintaining a substantial superatmospheric'pressure on the oil in said restricted stream and reaction zone. 7

In testimony whereof I aflix my signature.

LYMAN G. HUFF.

products from said enlarged chamber at a rate adequate to prevent any accumulation of non-vaporous liquid products in said chamber, and maintaining substantial superatmospheric pressure on the oil in said heating coil and enlarged chamber.

4. In oil cracking processes of the character in which the oil is heated while flowing in a stream of restricted cross-section through 

